OFFSET
1,1
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
FORMULA
Empirical: a(n) = 3*a(n-1) + 2*a(n-2) - a(n-3) - 9*a(n-4) + 16*a(n-5) - 48*a(n-6) - 21*a(n-7) + 8*a(n-8) + 3*a(n-9).
Empirical g.f.: 4*x*(205 + 52*x - 241*x^2 - 579*x^3 - 36*x^4 - 3382*x^5 - 1168*x^6 + 563*x^7 + 192*x^8) / (1 - 3*x - 2*x^2 + x^3 + 9*x^4 - 16*x^5 + 48*x^6 + 21*x^7 - 8*x^8 - 3*x^9). - Colin Barker, Nov 09 2018
EXAMPLE
Some solutions for n=5:
..3....0....1....2....0....0....1....3....2....1....0....3....1....0....0....3
..0....2....0....0....3....0....2....2....2....0....0....1....2....1....3....0
..3....2....3....3....3....2....1....0....3....2....0....2....1....0....0....0
..1....0....0....1....1....2....0....0....2....0....2....0....0....2....0....1
..0....2....2....2....1....2....3....3....0....0....0....0....0....3....3....3
..2....2....3....0....3....3....2....3....0....0....1....1....3....1....3....2
..1....0....1....3....1....3....3....0....1....1....0....0....3....1....3....1
..3....3....1....3....1....2....1....1....3....3....1....0....0....1....2....0
..0....1....1....3....3....3....0....2....0....2....2....0....0....0....1....0
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Oct 18 2014
STATUS
approved